Search

Silica-polyurea/polyuretane hybrid shell microcapsules (MCs) loaded with isophorone diisocyanate (IPDI) with long shelf-life and high thermal and chemical stability are prepared via emulsification followed by interfacial polymerization at the surface of oil droplets of the oil-in-water emulsion. The resultant MCs are aimed at self-healing performance in epoxy coatings. A commercially available, highly reactive polyisocyanate named tris(p-isocyanatophenyl) thiophosphate is successfully employed as shell forming agent, while triethoxyoctylsilane and hexadecyltrimethoxysilane (HDMS) are tested as �latent'' active hydrogen sources. The resulting MCs display core�shell morphology, spherical shape with diameter of 5�20 ?m, shell thickness ca. 1�2 ?m, and an IPDI core fraction of 69 and 65 wt %, when HDMS and triethoxyoctylsilane are employed, respectively. MCs exhibit an increased thermal stability, comparing with pure IPDI, which makes them robust enough to resist the thermal cycles involved in the coating's preparation. Stability of MCs inside specific solvents and chemicals, their chemical composition and shelf-life as well as effect of MCs on the epoxy curing are evaluated by Fourier transformed infrared spectroscopy. MCs, remarkably, show excellent environment stability and a long shelf-life of more than 3.5 months. Their addition to an epoxy formulation is found to heal damaged zones in the epoxy coating, as shown by scanning electron microscopy and electrochemical impedance spectroscopy. - 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48751. - 2019 Wiley Periodicals, Inc. The authors gratefully acknowledge the Qatar National Research Fund (a member of the Qatar Foundation) for NPRP Grant # 9?080?2?039, Qatar Shell, an end user and project partner, Sherwin Williams for providing the model coating formulation, CQE through the strategic project FCT?UID/QUI/00100/2019 and CERENA through the strategic project FCT?UID/ECI/04028/2019. M.V. gratefully acknowledges FCT through PhD fellowship of reference SFRH/BD/138717/2018. Scopus

The present work describes indium-zinc oxide (IZO) sputtering depositions onto several types of papers, using radio-frequency (RF) and direct current (DC) sputtering with a ceramic IZO target. The electrical and optical properties of the resulting materials were optimized; by studying the argon and oxygen gas flow rates and the sputtering power effects. At optimal deposition conditions, thin films of IZO were achieved with a low sheet resistance (about 20 Ω/sq) and an optical transmittance of ca. 80% in the visible spectrum range. These materials retained these properties for more than 8 months. Electrochromic devices (ECDs) with several configurations were built with those conductive papers and life cycling and contrast were measured for the ECDs. These devices exhibited a very good color contrast (as defined using L * a * b * color coordinates, = 32) and electrochromic cyclability up to 30,000 redox cycles.

A new 3D Proton Induced X-Ray Emission Tomography (PIXE-T) and Scanning Transmission Ion Microscopy Tomography (STIM-T) simulation software has been developed in Java and uses NVIDIA™ Common Unified Device Architecture (CUDA) to calculate the X-ray attenuation for large detector areas. A challenge with PIXE-T is to get sufficient counts while retaining a small beam spot size. Therefore a high geometric efficiency is required. However, as the detector solid angle increases the calculations required for accurate reconstruction of the data increase substantially. To overcome this limitation, the CUDA parallel computing platform was used which enables general purpose programming of NVIDIA graphics processing units (GPUs) to perform computations traditionally handled by the central processing unit (CPU). For simulation performance evaluation, the results of a CPU- and a CUDA-based simulation of a phantom are presented. Furthermore, a comparison with the simulation code in the PIXE-Tomography reconstruction software DISRA (A. Sakellariou, D.N. Jamieson, G.J.F. Legge, 2001) is also shown. Compared to a CPU implementation, the CUDA based simulation is approximately 30× faster.

A gas flow ionization chamber for use with on-axis scanning transmission ion microscopy tomography (STIM-T) has been developed. The entrance window is composed of a square silicon nitride membrane 100 nm thick and 1 mm2 in area. The use of this type of window does not add significantly to the energy resolution with the MeV H+ or He+ particles used in STIM, and proved to be resistant to high proton fluence in the irradiated spot. The ability of such detector to withstand direct beam hit with acceptable energy resolution makes it suitable for on-axis STIM-T, in this respect outperforming the more standard Si PIN diodes, which performance is known to degrade above fluences of ∼1010–1012 cm−2. The present in-line design while allowing easy mounting of the detector to the existing target chamber, has the peculiarity of providing a practical way of replacing the Si3N4 membrane in case it brakes while operating. The concept of gas ionization chamber under development is expected to become ideal for on-axis STIM-T experiments due to its low ageing during operation, and anticipated attainable speed and energy resolution.

Statins are efficient cholesterol-lowering medicines utilized worldwide. However, 10% of patients suffer from adverse effects specially related to skeletal muscle function. Pro- or anti-oxidant effects of statins have been reported. Here we hypothesized that statins induce muscle mitochondrial oxidative stress leading to mitochondrial permeability transition (MPT) which may explain statin muscle toxicity. Thus, our aims were to investigate the effects of statin chronic treatment on muscle mitochondrial respiration rates, MPT and redox state indicators in the context of hypercholesterolemia. For this purpose, we studied muscle biopsies of the hypercholesterolemic LDL receptor knockout mice (LDLr-/-) treated with pravastatin during 3 months. Plantaris, but not soleus muscle of treated mice showed significant inhibition of respiration rates induced by ADP (–14%), oligomycin (–20%) or FCCP (–40%). Inhibitions of respiratory rates were sensitive to EGTA (Ca2+ chelator), cyclosporin A (MPT inhibitor), ruthenium red (inhibitor of mitochondria Ca2+ uptake) and coenzyme Q10 (antioxidant), indicating that pravastatin treatment favors Ca2+ induced MPT. Diet supplementation with creatine (antioxidant) also protected treated mice against pravastatin sensitization to Ca2+ induced MPT. Among several antioxidant enzymes analyzed, only catalase activity was increased by 30% in plantaris muscle of pravastatin treated mice. Oxidized lipids, but not proteins biomarkers were identified in treated LDLr-/- plantaris muscle. Taken together, the present results suggest that chronic pravastatin administration to a model of familial hypercholesterolemia promotes mitochondrial dysfunctions in plantaris muscle that can be counteracted by antioxidants administered either in vitro (CoQ10) or in vivo (creatine). Therefore, we propose that inhibition of muscle mitochondrial respiration by pravastatin leads to an oxidative stress that, in the presence of calcium, opens the permeability transition pore. This mitochondrial oxidative stress caused by statin treatment also signals for cellular antioxidant system responses such as catalase upregulation. These results suggest that the detrimental effects of statins on muscle mitochondria could be prevented by co-administration of a safe antioxidant such as creatine or CoQ10.

Eukaryote genomes encode a surprisingly large number of noncoding transcripts. Around two-thirds of human transcribed loci do not encode protein, and many are intergenic and produce long (>200 nucleotides) noncoding RNAs (lncRNAs). Extensive analyses using comparative genomics and transcriptomics approaches have established that lncRNA sequence and transcription tend to turn over rapidly during evolution. Our appreciation of the biological roles of lncRNAs, based only on a handful of transcripts with well-characterized functions, is that lncRNAs have diverse roles in regulating gene expression. These proposed roles together with their rapid rates of evolution suggest that lncRNAs could contribute to the divergent expression patterns observed among species and potentially to the origin of new traits.

What causes the tissue-specific pathology of diseases resulting from mutations in housekeeping genes? Specifically, in spinocerebellar ataxia type 7 (SCA7), a neurodegenerative disorder caused by a CAG-repeat expansion in ATXN7 (which encodes an essential component of the mammalian transcription coactivation complex, STAGA), the factors underlying the characteristic progressive cerebellar and retinal degeneration in patients were unknown. We found that STAGA is required for the transcription initiation of miR-124, which in turn mediates the post-transcriptional cross-talk between lnc-SCA7, a conserved long noncoding RNA, and ATXN7 mRNA. In SCA7, mutations in ATXN7 disrupt these regulatory interactions and result in a neuron-specific increase in ATXN7 expression. Strikingly, in mice this increase is most prominent in the SCA7 disease-relevant tissues, namely the retina and cerebellum. Our results illustrate how noncoding RNA-mediated feedback regulation of a ubiquitously expressed housekeeping gene may contribute to specific neurodegeneration.

An innovative biosensor assembly relying on a simple and straightforward in-situ construction is presented to monitor urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) down to the pmol/L level. The sensing film of the biosensor consisted of a molecularly imprinted polymer (MIP) layer for 8-OHdG assembled on a gold electrode through electropolymerization of monomer combined with the template. The analytical features of the resulting biosensor were assessed by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Some experimental parameters such as the initial concentration of the monomer and the ratio template-monomer were investigated and optimized in order to finely tune the performance of the MIP-based sensor. Under optimal conditions, the developed biosensor was able to rebind 8-OHdG with a linear response against EIS from 0.1 to 100pg/ml 3.5-3500 pM. The interference of coexisting species was tested, also with calibrations on urine samples, and good selectivity towards 8-OHdG was obtained. RAMAN spectroscopy, FTIR and SEM evaluations of the prepared films confirmed the formation of a polyphenol thin-film on the electrode surface. The presence and distribution of the imprinted cavities on the MIP layer was confirmed by confocal microscopy imaging of the film, after a post-treatment with Fluorescein Isothiocyanate (FITC) labeled 8-OHdG antibody. Overall, this label-free biosensor for urinary 8-OHdG detection constitutes a promising low-cost alternative to the conventional immunoassay approaches, due to its simplicity, stability, high sensitivity and selectivity for biological sample assays, opening new doors for other applications.

Recently, nano-macro dual-porous, three-dimensional (3D) glass structures were developed for use as bioscaffolds for hard tissue regeneration, but there have been concerns regarding the interconnectivity and homogeneity of nanopores in the scaffolds, as well as the cytotoxicity of the environment deep inside due to limited fluid access. Therefore, mercury porosimetry, nitrogen absorption, and TEM have been used to characterize nanopore network of the scaffolds. In parallel, viability of MG 63 human osteosarcoma cells seeded on scaffold surface was investigated by fluorescence, confocal and electron microscopy methods. The results show that cells attach, migrate and penetrate inside the glass scaffold with high proliferation and viability rate. Additionally, scaffolds were implanted under the skin of a male New Zealand rabbit for in vivo animal test. Initial observations show the formation of new tissue with blood vessels and collagen fibers deep inside the implanted scaffolds with no obvious inflammatory reaction. Thus, the new nano-macro dual-porous glass structure could be a promising bioscaffold for use in regenerative medicine and tissue engineering for bone regeneration.

A combination of simultaneous Proton Induced X-Ray Emission Tomography (PIXE-T), Scanning Transmission Ion Microscopy Tomography (STIM-T) and Rutherford Backscattering Spectrometry (RBS) can produce 3D quantitative elemental maps with a resolution on the micron scale. This combination is being developed at the Instituto Tecnologico e Nuclear-Instituto Superior Tecnico (ITN-IST) nuclear microprobe facility. To reconstruct complex datasets, iterative procedures are usually applied. GPU-accelerated PIXE-T/STIM-T simulation software has been developed and used in conjunction with an iterative reconstruction software DISRA and an MLEM algorithm to reconstruct data produced by simulating a PIXE-T experiment of a phantom.

No abstract available.

Antioxidants are compounds that protect cells against the damaging effects of reactive oxygen species (ROS) such as singlet oxygen, superoxide, peroxyl radicals, hydroxyl radicals and peroxynitrite. Oxidative damage occurs to cells in vivo and in vitro from exposure to free radicals generated by exogenous agents (e.g., radiation, chemicals, hyperoxia) and endogenous processes such as normal cellular metabolism. An imbalance between antioxidants and ROS results in oxidative stress, leading to cellular damage. Oxidative stress (OS) has been linked to cancer, ageing, atherosclerosis, ischemic injury, inflammation, and neurodegenerative diseases. Under extreme oxidative conditions, or if the antioxidant protective mechanisms of cells are compromised, cellular injury and death may occur. Early mammalian embryos are susceptible to damage from reactive oxygen species, and they increase the production of oxygen free radicals when cultured in vitro. ROS generation results from mitochondrias oxidative phosphorylation. The electrons will leak from the inner mitochondrial membranes, being transferred by the oxygen molecule, resulting in an unpaired electron in the orbit. This leaking results in the generation of the superoxide molecules. ROS can also be generated by the cytoplasmic NADPH-oxidase, cytochrome p450 enzymes and the xanthine oxidoreductase enzymes. The excess of OS can have negative effects on the cellular environment and can result in impaired cellular growth in the embryo or apoptosis resulting in embryo fragmentation. Similarly to what happens in females, oxidative energy production in males is inevitably associated with the generation of ROS excessive concentrations of which can lead to cellular pathology. It has been established that ROS can function as signaling molecules and evidence is emerging that sperm may generate low and controlled concentrations of ROS, specifically O2-H2O2, as well as other species such as nitric oxide (NO), which, in his turn, act to mediate the processes of capacitation, hyperactivation and acrosome reaction crucial to the acquisition of fertilizing ability. In the present review the most important antioxidants and their mechanisms of action related to animal reproduction, are discussed.

We report on the preparation of a bioactive CaO–SiO2 monolithic scaffold with interconnected bimodal nanomacro porosity, which simulates the morphology of a natural trabecular bone, by a newly developed modified sol-gel process. This method inherently creates nanopores, whose average diameter can be tailored to approximately 5–20 nm by solvent exchange. To achieve interconnected macroporosity (pores ∼5–300 μm in size), a polymer [poly(ethylene oxide)] is added, which causes phase separation simultaneously with the sol-gel transition. High-resolution scanning electron microscopy and mercury intrusion porosimetry demonstrate a high degree of three-dimensional interconnectivity and sharp distributions of pore size. In vitro bioactivity tests in simulated body fluid (SBF) show bioactivity of the material after soaking for approximately 5 h, as verified by the formation of a hydroxyapatite layer deep into the scaffold structure. Analysis of the SBF after the reaction indicates the dissolution of the samples, another desired feature of temporary scaffolds for bone regeneration. MG63 osteoblast-like cells seeded on our sol-gel glass samples responded better to samples with nanopores enlarged by a solvent exchange process than to the one with normal nanopores. Thus, the benefits of the high surface area achieved by sol-gel and solvent exchange procedures are most clearly demonstrated for the first time.

Development of optimal scaffolds for bone tissue engineering and regeneration is still a challenge, since many materials and structures have been proposed but few have reached clinical expectations. This work reports on the preparation and characterization of SiO2-CaO and SiO2-CaO-P2O5 sol–gel derived monoliths, with potential application as glass scaffolds for bone regeneration, exhibiting a nano/macro trimodal pore size distribution, including pores of ~100’s of micrometers (μm), several microns and just a few nanometers (nm) in size. Interconnected macropores (~20–200 μm) have been obtained in the present work by polymerization-induced spinodal phase separation along with the sol–gel transition, when a water soluble polymer [poly(ethylene oxide)] was added to the sol–gel solution; the several-micron pores are spherical and isolated and might be the result of secondary phase separation by nucleation-growth mechanism; the interconnected nanopore (~5–25 nm) structure of the macroporous gel skeleton, on the other hand, was tailored by solvent exchange procedures. The morphological and textural characterization of these materials was performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray ultra microscopy (XuM), nitrogen adsorption and mercury intrusion porosimetry. The factors affecting the porosity exhibited by the scaffolds, such as glass composition and solvent exchange conditions, have been assessed.

The local order around ion-implanted Er 3+ ions in SiO 2 –TiO 2 –HfO 2 thin films prepared by sol–gel, was studied by extended X-ray absorption fine structure at the Er-L III edge. Both the first and second coordination shells of Er 3+ were analyzed for different heat-treatments. While the first coordination shell always consisted of ∼6–7 oxygen atoms at distances varying between 2.23 and 2.27 A, the structure of the second shell was found to vary with the film composition and heat-treatment. Namely, whereas Si was found to be the only second neighbor of erbium in binary SiO 2 –TiO 2 films, the addition of HfO 2 caused a preferential replacement of Si by Hf. The post-implantation thermal treatments also played a fundamental role in determining the final environment of the erbium ions.

Sol–gel is a very convenient technique for the fabrication of high quality thin glass films, optical planar waveguides and photonic bandgap structures. Ion exchange, on the other hand, is a well-established technique to fabricate high quality waveguides in glass and integrated optical amplifiers made by this technique are commercially available. The possible integration of the sol–gel and ion-exchange techniques for the fabrication of passive and active (rare-earth doped) channel waveguides in integrated optic devices has recently gained interest. A general overview of the fabrication of passive and active films and planar waveguides by sol–gel is followed by a brief description of waveguide fabrication by ion exchange and the possible integration between the two processing technologies.

Erbium/ytterbium-doped photonic bandgap materials and structures have been prepared by sol–gel processing, in the form of 1-D structures of the single (Fabry–Perot) and coupled (double) microcavity types, consisting of multilayer stacks of silica and titania. Such multilayers were deposited by spin-coating on silica glass substrates and their reflection spectra were measured in the near infrared range. It was found that, by varying the detection angle, it is possible to broaden the Er3+ emission at 1.5 μm, irrespective of the excitation wavelength (514.5 or 980 nm), which is important for applications where broadband emission is necessary, for example for all-optical amplification in dense wavelength division multiplexing (WDM) systems. A remarkable full width at half maximum (FWHM) of 52 nm was achieved for the Er3+ emission peak at 1.5 μm, when this rare-earth (RE) dopant was incorporated in a pure silica glass cavity layer. Other described phenomena include Er3+ photoluminescence enhancement from microcavities, compared with doped Bragg mirrors and films and enhanced Yb3+→Er3+ energy transfer in co-doped photonic crystal structures.

Resumo: A síndroma de Mounier-Kuhn é uma doença rara, de etiologia desconhecida e que se presume subdiagnosticada. Cursa frequentemente com infecções respiratórias de repetição e bronquiectasias. A clínica inespecífica, semelhante a outras patologias supurativas brônquicas crónicas, dificulta o diagnóstico, muitas vezes efectuado vários anos após o início dos sintomas. Os autores apresentam uma revisão da literatura a propósito de dois casos clínicos que ilustram a heterogeneidade e as dificuldades diagnósticas desta entidade nosológica. Um dos doentes encontrava-se em idade pediátrica na altura do diagnóstico e outro na quarta década de vida. Abstract: The incidence of the syndrome may be greater than is suspected. Patients present with recurrent respiratory infections and bronchiectasis. The symptoms are non-specific and indistinguishable from those of other chronic respiratory diseases. The diagnosis is often made several years after the first clinical complaints. The authors perform a brief review of the literature and report two cases of Mounier--Kuhn syndrome. One of the patients was diagnosed in childhood and the other in the fourth decade of life. Palavras-chave: Síndroma de Mounier-Kuhn, traqueobroncomegalia, infecções respiratórias de repetição, Key-words: Mounier-Kuhn syndrome, tracheobronchomegaly, recurrent respiratory infections

This paper reports on the study of the effects of silver (Ago) nanoparticles on the optical and spectroscopic properties of Er3+-doped silica-based gels and glasses, including active bulk materials and planar waveguides for integrated optics. Two different procedures for silver and erbium ion incorporation into the glassy matrices have been investigated: the direct incorporation of a metal salt (AgNO3 and/or Er(NO3)3) into the sol–gel solution, as well as a modified sol–gel process, based on pore-doping of a precursor gel with AgNO3 and/or Er(NO3)3 solutions. The study of the parameters determining the average size and size distribution of the nanoparticles, together with their influence on the sol–gel material densification and Er3+ photoluminescence at 1.5 μm, has been performed by means of transmission electron microscopy, plus ultra-violet/visible and photoluminescence spectroscopies. The Ago colloidal nanoparticles, obtained by thermal precipitation, were approximately spherical, homogeneously distributed and they exhibited an average size between ∼2 and 15 nm, depending on the silver content and heat treatment performed. They are shown to be responsible for a remarkable enhancement of the Er3+ photoluminescence intensity, which is mainly due to the increase of the local electric field around the Er3+ ions, due to the surface plasmon resonance of the Ago nanoparticles.

Recovery of point defects and local phase transitions were studied in the neighbourhood of implanted 111mCd (low fluence of 1.5 × 1012 at/cm2) into undoped and 2%Nb-doped SrTiO3 single crystals by means of the perturbed angular correlation technique. Measurements in the as implanted state and after subsequent 720 °C and 1000 °C 20 min air annealings have shown the recovery of defects in the Cd neighbourhood. After annealing, low temperature experiments have studied the cubic-to-tetragonal and the orthorhombic-to-rhombohedral phase transitions at the atomic scale. In the undoped samples it was found at 77 K, the coexistence of cubic and tetragonal single oriented phases. By further cooling the samples to 10 K a single low – symmetry phase is formed. On Nb-doped samples the phase transitions are hindered, being the lattice symmetries also affected in the Cd atomic neighbourhood. These effects appear to be particularly dependent on the dopant concentration.

Radioactive 73As ions were implanted into a ZnO single crystal at room temperature with 60 keV up to a fluence of 2×1013 cm−2. Subsequently, the angular emission channeling patterns of emitted conversion electrons were recorded by means of a position-sensitive detector in the as-implanted state and following annealing up to 900 ∘C, and were compared to simulated emission yields for a variety of different lattice sites. We find that As does not occupy substitutional O sites, but mainly occupies the substitutional Zn sites. The fraction of As on O sites was at most a few per cent. Arsenic in ZnO is thus an interesting example of an impurity in a semiconductor where the major impurity lattice site is determined by atomic size and electronegativity rather than its position in the periodic system. Possible consequences with respect to the role of arsenic as a p-type dopant in ZnO are being discussed.

Technical progress on silicon pad electron detectors, currently used in emission channelling experiments to study lattice location of radioactive dopants and impurities in single crystals, is reported. Noise and trigger efficiency improvements are achieved by using 500 μm and 1 mm thick detectors coupled to a cooled readout system. The static properties, noise, gamma ray and electron trigger efficiency and energy resolution for different temperatures under air and vacuum were measured. The advantages of the future implementation of 1 mm silicon pad detectors with cooled self-triggering readout chips are discussed.

International audience; We present here a new development of the TomoRebuild software package, to perform quantitative Particle Induced X-ray Emission Tomography (PIXET) reconstruction. X-ray yields are obtained from the GUPIX code. The GUPIX data base is available for protons up to 5 MeV and also in the 20–100 MeV energy range, deuterons up to 6 MeV, 3He and alphas up to 12 MeV. In this version, X-ray yields are calculated for thin samples, i.e. without simulating X-ray attenuation. PIXET data reconstruction is kept as long as possible independent from Scanning Transmission Ion Microscopy Tomography (STIMT). In this way, the local mass distribution (in g/cm3) of each X-ray emitting element is reconstructed in all voxels of the analyzed volume, only from PIXET data, without the need of associated STIMT data. Only the very last step of data analysis requires STIMT data, in order to normalize PIXET data to obtain concentration distributions, in terms of normalized mass fractions (in μg/g). For this, a noise correction procedure has been designed in ImageJ. Moreover sinogram or image misalignment can be corrected, as well as the difference in beam size between the two experiments. The main features of the TomoRebuild code, user friendly design and modular C++ implementation, were kept. The software package is portable and can run on Windows and Linux operating systems. An optional user-friendly graphic interface was designed in Java, as a plugin for the ImageJ graphic software package. Reconstruction examples are presented from biological specimens of Caenorhabditis elegans – a small nematode constituting a reference model for biology studies. The reconstruction results are compared between the different codes TomoRebuild, DISRA and JPIXET, and different reconstruction methods: Filtered BackProjection (FBP) and Maximum Likelihood Expectation Maximization (MLEM).

This work was partially supported by the Portuguese Science Foundation (FCT-MEC) through the projects EXCL/CTM-NAN/0201/2012, Pest-C/CTM/LA0025/2013-14, Pest-C/EQB/LA0006/2013-14, PTDC/BBB-BEP/0753/2012 and the ERC Advanced Grant (INVISIBLE, contract number 228144). Geobacter sulfurreducens cells were kindly provided by Prof. Derek Lovley from University of Massachusetts (USA). We would like to thank to Dr. Daniela Nunes for the SEM images. Electrochemically active bacteria (EAB) have the capability to transfer electrons to cell exterior, a feature that is currently explored for important applications in bioremediation and biotechnology fields. However, the number of isolated and characterized EAB species is still very limited regarding their abundance in nature. Colorimetric detection has emerged recently as an attractive mean for fast identification and characterization of analytes based on the use of electrochromic materials. In this work, WO 3 nanoparticles were synthesized by microwave assisted hydrothermal synthesis and used to impregnate non-treated regular office paper substrates. This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method. The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept. G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04, and a response time of two hours. publishersversion published

This work was aimed at understanding the structure of SiO2–MO2 (M = Ti, Zr, Hf) and SiO2–HfO2–MO2 (M = Ti, Zr) materials, used as mixed oxide glass hosts for Er3+ ions in the fabrication of optical planar waveguides by sol-gel processing. This structural study was performed by Waveguide Raman Spectroscopy (WRS), complemented with X-ray diffraction (XRD). The admixture of TiO2 to HfO2, SiO2–HfO2 and HfO2–ZrO2 compositions was found to cause precipitation of nanocrystals of tetragonal HfO2 or ZrO2, or the formation of hafnia-titania mixed crystals, depending on the HfO2/TiO2 molar ratio.

Sol–gel processing is a cheap and versatile method of producing silica on silicon films for planar integrated optics. It leads to high Er incorporation and to easy incorporation of Ag, that can intensify the rare-earth photoluminescence. Different heat treatments and compositions must be tested to optimise the properties of the films grown, and the annealing may lead to redistribution of the elements into different layers, including of H present in the films. We have analysed sol–gel silica films doped with Er and Ag and subject to different annealing procedures with Rutherford backscattering (RBS) and elastic recoil detection (ERDA), leading to a large quantity of complex spectra. We developed an artificial neural network (ANN) able to analyse simultaneously the RBS and ERDA spectra collected from one sample. Non-standard network architecture was necessary due to the complexity of the problem. The optimised ANN is applied to experimental data leading to results that are practically as accurate as those obtained with a conventional data analysis code.

The characteristics of rare-earth luminescence in selected sol–gel derived confined structures have been examined. Erbium and erbium/ytterbium doped photonic materials and structures have been prepared by sol–gel processing, in the form of silicate optical planar waveguides, modified with titania and hafnia, and 1-D photonic bandgap structures consisting of multilayer stacks of silica and titania. The Er 3+ ions were found to be sensitive probes of the waveguide glass matrix structure, especially when hafnia-containing nanocrystallites were present, which narrowed and resolved different Stark components of the photoluminescence peaks. In 1-D Fabry–Perot coupled microcavities, efficient energy transfer was observed from Yb 3+ to Er 3+ ions when these were present simultaneously in the same defect layer, but not when the two types of ions were isolated in separate defect layers.

We implanted silica–titania sol–gel films with 3 × 1015 at./cm2, 180 keV Er+ and 6 × 1016 at./cm2, 140 keV Ag+ ions. The energies were chosen so that the profiles of Ag and Er overlap. RBS and ERDA were used to study the behaviour of Ag, Er and H during the heat treatments used to densify the films. Implantation causes H depletion at the film surface and an increase in H concentration just beneath the implanted Ag and Er profiles. The total H content decreases by 27% to 75% during implantation. During annealing the H content decreases, with an almost complete H loss after annealing for 35 min at 800 °C. The Ag profile remains stable up to 600 °C. Above 700 °C Ag becomes increasingly mobile. Annealing at 800 °C for 35 min results in a nearly constant Ag distribution in the film. The Er profile remains unchanged with heat treatment up to the maximum temperature used (800 °C).

Erbium-doped photonic materials and structures have been prepared by sol-gel, in the form of silica-hafnia based optical planar waveguides and 1-D photonic bandgap structures consisting of alternating silica and titania layers. The Er 3+ ions were found to be sensitive probes of the waveguide glass matrix structure, especially when hafnium-containing nanocrystallites were present, which narrowed and resolved different Stark components in the photoluminescence peaks. In 1-D Fabry-Perot microcavities, on the other hand, efficient energy transfer was observed from Yb 3+ to Er 3+ ions when these were present simultaneously in the same defect layer, but not when the two types of ions were isolated in separate defect layers of coupled microcavities.

A chemostat containing a mixed microbial community was operated with a hydraulic retention time of 48 h under cyclic aerobic/anoxic conditions while receiving a feed containing benzoate and pyruvat...

This paper studies the dc and ac impedance behaviour of undoped ZnO thin films produced by spray pyrolysis and rf magnetron sputtering under UV light illumination, at room temperature, emphasising the role that the crystallite size, structure, surface morphology and the state of surface have on the electrical responsivities obtained. The results achieved show that the sputtered films with crystal sizes of about 4 nm exhibit dc electrical UV responsivities of 108. On the other hand, the spray pyrolysis films exhibit the lowest dc responsivities, due the high crystal sizes and state of surface contamination, to which very good capacitance responses were obtained, mainly due to the degree of porosity exhibit by these films when produced at low temperatures. Based on that, a two-phase electrical model is proposed to explain the set of behaviours observed.

Er 3+ -doped silica-titania planar waveguides, prepared by sol-gel processing, have a tendency to exhibit ar eversible photoluminescence (PL) quenching phenomenon at 1.5 µm, when they are not fully densified. In the present paper, the presence of porosity and OH species associated with a simultaneous decrease in the Er 3+ PL intensity and lifetime are followed in detail by infrared and m-line spectroscopies. Different chemical compositions and EtOH/precursor ratios, as well as optimized heat treatments, have been used in order to ensure the preparation of fully densified waveguides with enhanced spectroscopic properties. Both the Er 3+ PL spectra and the fluorescence lifetimes at 1.5 µ mh ave been determined in the SiO2-TiO2-AlO1.5-ErO1.5, SiO2-HfO2-AlO1.5-ErO1.5 and SiO2- HfO2-TiO2-AlO1.5-ErO1.5 systems, as a function of the matrix composition and Er 3+ ion concentration. These waveguides, densified at 900 ◦ C, appear to offer the best performance in terms of stability and strength of the PL signal.

The photoluminescence efficiency of Er-doped silica-titania planar waveguides, prepared by sol-gel processing, may in principle be enhanced through the incorporation of silver metal particles. On the other hand, the presence of residual OH groups limits the optical activity of the Er3+ ions. In this work, we have used Rutherford Backscattering Spectrometry (RBS), combined with Elastic Recoil Detection Analysis (ERDA), in order to study the incorporation of Ag and H species as a function of the heat treatments used to densify the sol-gel films. Ultraviolet–visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to support and expand the interpretation of the RBS and ERDA data. The RBS results indicate a homogeneous distribution of Er in the as-deposited films. On the contrary, Ag displays a bimodal in-depth profile, centred at the air/film and film/Si substrate interfaces. Heat treatments at up to 700°C eventually lead to in-diffusion and segregation of most of the Ag species at the latter interface. The hydrogen concentration reaches minimum values after heat treatments at 500 and 900°C, with apparently larger values for temperatures in between. During these heat treatments, the Er profile remains stable.

The photoluminescence (PL) efficiency of Er-doped silica–titania planar waveguides, prepared by sol–gel processing, may be enhanced through the incorporation of neutral Ag metal particles. However, the presence of residual Si–OH groups and the limited reproducibility of the doping process limit the optical activity of the Er3+ ions. We have used Rutherford backscattering spectrometry (RBS) combined with elastic recoil detection analysis (ERDA) to study the incorporation behaviour of Ag and H atoms during the heat treatments used to densify the films. These were deposited by sol–gel spin-coating on single crystal Si or silica-buffered Si substrates (∼5 μm thick silica buffer layer). The results indicate a homogeneous distribution of Er in the as-deposited films. On the contrary, Ag displays a bimodal in-depth profile centred at the film surface and at the film/substrate interface. Annealing up to 700 °C leads to in-diffusion and concentration of all the Ag species at the latter interface. The H concentration maintains nearly the same values after annealing at 500 and 900 °C, with larger values for temperatures in between. During heat treatment the Er profile remains stable.

Er 3+ -doped silicate planar waveguides are important for the fabrication of integrated optics amplifiers. This paper presents a study of reversible photoluminescence (PL) quenching in Er 3+ -doped silica–titania planar waveguides, prepared by sol–gel processing. The infrared absorption and PL spectra of these waveguides at 1.5 μm are reported as a function of different heat treatments and time of exposure to various atmospheres. The corresponding emission lifetimes have also been measured in selected cases. Several samples have shown a decrease in the 1.5 μm PL peak intensity, after a few days in air at RT and a longer decrease when kept in an ultrasonic water bath. This change is found to be reversible, however, as long as a subsequent heat treatment at temperatures as low as 200 °C is performed on the same samples. In addition, when these are kept under a controlled atmosphere with low moisture contents (such as in liquid nitrogen, or in a controlled atmosphere glove-box), there is a decrease in the rate at which the PL decreases. A heat treatment in a vacuum furnace, at a relatively high temperature (∼700–900 °C), is shown to prevent most of the PL quenching. We examine the possible mechanisms involved, including the effects of residual OH groups and atmospheric H 2 O, studied by infrared spectroscopy, plus the role of film porosity in the PL quenching phenomenon.

The present paper is focused on multilayer Er3+-doped silica-titania planar waveguides, co-doped with silver, which were prepared by spin-coating on silica glass, or buffered single crystal silicon substrates. The single layer thickness (∼0.4 μm) and refractive index (∼1.60–1.63) were measured by spectroscopic ellipsometry at 715 nm. The thickness of the waveguides (measured by mechanical profilometry) was ∼1 μm and their optical propagation losses were measured at different laser wavelengths (488 nm, 514 nm and 633 nm), exhibiting an approximately Rayleigh-like behavior. The thermal precipitation of silver nanocrystallites was achieved, both in air and under a controlled atmosphere (dry nitrogen) and these were characterized by visible absorption spectroscopy, which clearly showed the development of a plasmon absorption band near 415 nm, by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The Er3+ metastable level lifetimes for the emission at ca. 1.54 μm were found to be ca. 4–6 ms, for Er3+ concentrations varying between 0.2–2.0 mol% (or ∼(0.4–4.4) × 1020 ions/cm3), but no significant variation was observed with the Ag concentration added (up to 2.5 mol%).

Sol-gel processing is becoming one of the cheapest and most versatile methods for the fabrication of passive and active planar waveguides for integrated optics, in particular for the silica-on-silicon type. The present paper focuses on some recent work in our group on both passive and active (Er3+-doped) silica–titania inorganic and hybrid waveguides, considering in detail their densification behaviour, structure and optical properties. Recent advanced topics, such as nanocrystalline active waveguides prepared by by sol–gel method, are also addressed. The main results to be presented will deal first with the structural evolution during the densification of inorganic and hybrid silica-titania waveguides. Then, the fluorescence behaviour of active waveguides, doped with Er3+ ions, will also be described. And finally silver co-doped nanocrystalline waveguides, will be considered in detail, with particular emphasis on, firstly, the influence of preparation conditions on optical properties such as the...

Testing and further investigation of organosilica microspheres functionalized with aqueous glycerol as solid curing agents for polyurethane (PU) foams confirms the potential of these materials to cure better and greener PU foams. The developed microspheres were found to be stable in the foam precursor mixture, allowing handling and mixing of the foam cans, and were shown to provide a slight improvement of the curing speed. The foams obtained from the froth containing the microspheres were found to maintain the level of quality of reference foam samples. Termed “GreenCaps”, these microspheres will subsequently be tested in pre-commercial applications.

The increase of conductivity of electrolytes favors the current production in microbial fuel cells (MFCs). Adaptation of cell cultures to higher ionic strength is a promising strategy to increase electricity production. The bacterium Geobacter sulfurreducens is considered a leading candidate for MFCs. Therefore, it is important to evaluate the impact of the ionic strength on the functional properties of key periplasmic proteins that warrants electron transfer to cell exterior. The effect of the ionic strength on the functional properties of triheme cytochrome PpcA, the most abundant periplasmic cytochrome in G. sulfurreducens, was investigated by NMR and potentiometric methods. The redox properties of heme IV are the most affected ones. Chemical shift perturbation measurements on the backbone NMR signals, at increasing ionic strength, also showed that the region close to heme IV is the most affected due to the large number of positively charged residues, which confer a highly positive electrostatic surface around this heme. The shielding of these positive charges at high ionic strength explain the observed decrease in the reduction potential of heme IV and shows that PpcA was designed to maintain its functional mechanistic features even at high ionic strength.

Endogenously expressed transcripts that are posttranscriptionally regulated by the same microRNAs (miRNAs) will, in principle, compete for the binding of their shared small noncoding RNA regulators and modulate each other's abundance. Recently, the levels of some coding as well as noncoding transcripts have indeed been found to be regulated in this way. Transcripts that engage in such regulatory interactions are referred to as competitive endogenous RNAs (ceRNAs). This novel layer of posttranscriptional regulation has been shown to contribute to diverse aspects of organismal and cellular biology, despite the number of functionally characterized ceRNAs being as yet relatively low. Importantly, increasing evidence suggests that the dysregulation of some ceRNA interactions is associated with disease etiology, most preeminently with cancer. Here we review how posttranscriptional regulation by miRNAs contributes to the cross-talk between transcripts and review examples of known ceRNAs by highlighting the features underlying their interactions and what might be their biological relevance.

Why protein-coding genes express transcripts with longer 3’untranslated regions (3’UTRs) in the brain rather than in other tissues remains poorly understood. Given the established role of 3’UTRs in post-transcriptional regulation of transcript abundance and their recently highlighted contributions to miRNA-mediated cross-talk between mRNAs, we hypothesized that 3’UTR lengthening enhances coordinated expression between functionally-related genes in the brain. To test this hypothesis, we annotated 3’UTRs of human brain-expressed genes and found that transcripts encoding ion channels or transporters are specifically enriched among those genes expressing their longest 3’UTR extension in this tissue. These 3’UTR extensions have high density of response elements predicted for those miRNAs that are specifically expressed in the human frontal cortex. Importantly, these miRNA response elements are more frequently shared among ion channel/transporter-encoding mRNAs than expected by chance. This indicates that miRNA-mediated cross-talk accounts, at least in part, for the observed coordinated expression of ion channel/transporter genes in the adult human brain.We conclude that extension of these genes’ 3’UTRs enhances the miRNA-mediated cross-talk among their transcripts which post-transcriptionally regulates their mRNAs’ relative levels.

International audience; The tomographic reconstruction of biological specimens requires robust algorithms, able to deal with low density contrast and low element concentrations. At the IST/ITN microprobe facility new GPU-accelerated reconstruction software, JPIXET, has been developed, which can significantly increase the speed of quantitative reconstruction of Proton Induced X-ray Emission Tomography (PIXE-T) data. It has a user-friendly graphical user interface for pre-processing, data analysis and reconstruction of PIXE-T and Scanning Transmission Ion Microscopy Tomography (STIM-T). The reconstruction of PIXE-T data is performed using either an algorithm based on a GPU-accelerated version of the Maximum Likelihood Expectation Maximisation (MLEM) method or a GPU-accelerated version of the Discrete Image Space Reconstruction Algorithm (DISRA) (Sakellariou (2001) [2]). The original DISRA, its accelerated version, and the MLEM algorithm, were compared for the reconstruction of a biological sample of Caenorhabditis elegans - a small worm. This sample was analysed at the microbeam line of the AIFIRA facility of CENBG, Bordeaux. A qualitative PIXE-T reconstruction was obtained using the CENBG software package TomoRebuild (Habchi et al. (2013) [6]). The effects of pre-processing and experimental conditions on the elemental concentrations are discussed.

Endogenously expressed transcripts that are posttranscriptionally regulated by the same microRNAs (miRNAs) will, in principle, compete for the binding of their shared small noncoding RNA regulators and modulate each other’s abundance. Recently, the levels of some coding as well as noncoding transcripts have indeed been found to be regulated in this way. Transcripts that engage in such regulatory interactions are referred to as competitive endogenous RNAs (ceRNAs). This novel layer of posttranscriptional regulation has been shown to contribute to diverse aspects of organismal and cellular biology, despite the number of functionally characterized ceRNAs being as yet relatively low. Importantly, increasing evidence suggests that the dysregulation of some ceRNA interactions is associated with disease etiology, most preeminently with cancer. Here we review how posttranscriptional regulation by miRNAs contributes to the cross-talk between transcripts and review examples of known ceRNAs by highlighting the features underlying their interactions and what might be their biological relevance.

Numerous structural studies have been carried out so far to elucidate the nature of the so-called germanate anomaly, but the correct structural model is still unknown. The objective of the present paper is to shed further light on the structure of alkali germanate glasses, namely those containing sodium and cesium oxides. Two series of glass samples were prepared, having molar compositions (100−x)GeO2·xM2O (M=Na and 0⩽x⩽35, or M=Cs and 0⩽x⩽25). Polarized Raman and infrared absorption spectra were recorded for these glasses, as a function of the alkali content; infrared reflectivity measurements were also carried out and Kramers–Kronig analysis of the near-normal incidence spectra were compared with the polarized Raman spectra of the glasses. An overall structural picture has emerged, which is compatible with the presence of a fraction of higher coordinated Ge atoms, either five-fold or six-fold.

BACKGROUND: Recent reports have highlighted instances of mRNAs that, in addition to coding for protein, regulate the abundance of related transcripts by altering microRNA availability. These two mRNA roles - one mediated by RNA and the other by protein - are inter-dependent and hence cannot easily be separated. Whether the RNA-mediated role of transcripts is important, per se, or whether it is a relatively innocuous consequence of competition by different transcripts for microRNA binding remains unknown. RESULTS: Here we took advantage of 48 loci that encoded proteins in the earliest eutherian ancestor, but whose protein-coding capability has since been lost specifically during rodent evolution. Sixty-five percent of such loci, which we term 'unitary pseudogenes', have retained their expression in mouse and their transcripts exhibit conserved tissue expression profiles. The maintenance of these unitary pseudogenes' spatial expression profiles is associated with conservation of their microRNA response elements and these appear to preserve the post-transcriptional roles of their protein-coding ancestor. We used mouse Pbcas4, an exemplar of these transcribed unitary pseudogenes, to experimentally test our genome-wide predictions. We demonstrate that the role of Pbcas4 as a competitive endogenous RNA has been conserved and has outlived its ancestral gene's loss of protein-coding potential. CONCLUSIONS: These results show that post-transcriptional regulation by bifunctional mRNAs can persist over long evolutionary time periods even after their protein coding ability has been lost.

A large proportion of functional sequence within mammalian genomes falls outside protein-coding exons and can be transcribed into long RNAs. However, the roles in mammalian biology of long noncoding RNA (lncRNA) are not well understood. Few lncRNAs have experimentally determined roles, with some of these being lineage-specific. Determining the extent by which transcription of lncRNA loci is retained or lost across multiple evolutionary lineages is essential if we are to understand their contribution to mammalian biology and to lineage-specific traits. Here, we experimentally investigated the conservation of lncRNA expression among closely related rodent species, allowing the evolution of DNA sequence to be uncoupled from evolution of transcript expression. We generated total RNA (RNAseq) and H3K4me3-bound (ChIPseq) DNA data, and combined both to construct catalogues of transcripts expressed in the adult liver of Mus musculus domesticus (C57BL/6J), Mus musculus castaneus, and Rattus norvegicus. We estimated the rate of transcriptional turnover of lncRNAs and investigated the effects of their lineage-specific birth or death. LncRNA transcription showed considerably greater gain and loss during rodent evolution, compared with protein-coding genes. Nucleotide substitution rates were found to mirror the in vivo transcriptional conservation of intergenic lncRNAs between rodents: only the sequences of noncoding loci with conserved transcription were constrained. Finally, we found that lineage-specific intergenic lncRNAs appear to be associated with modestly elevated expression of genomically neighbouring protein-coding genes. Our findings show that nearly half of intergenic lncRNA loci have been gained or lost since the last common ancestor of mouse and rat, and they predict that such rapid transcriptional turnover contributes to the evolution of tissue- and lineage-specific gene expression., Author Summary The best-understood portion of mammalian genomes contains genes transcribed into RNAs, which are subsequently translated into proteins. These genes are generally under high selective pressure and deeply conserved between species. Recent publications have revealed novel classes of genes, which are also transcribed into RNA but are not subsequently translated into proteins. One such novel class are long noncoding RNA (lncRNA). LncRNA loci are controlled in a similar manner to protein-coding genes, yet are more often expressed tissue-specifically, and their conservation and function(s) are mostly unknown. Previous reports suggest that lncRNAs can affect the expression of nearby protein-coding genes or act at a distance to control broader biological processes. Also, lncRNA sequence is poorly conserved between mammals compared with protein-coding genes, but how rapidly their transcription evolves, particularly between closely related species, remains unknown. By comparing lncRNA expression between homologous tissues in two species of mouse and in rat, we discovered that lncRNA genes are “born” or “die” more rapidly than protein-coding genes and that this rapid evolution impacts the expression levels of nearby coding genes. This local regulation of gene expression reveals a functional role for the rapid evolution of lncRNAs, which may contribute to biological differences between species.